Half the Crab I Used to Be

Don't let this crustacean fool you with his crab-like appearance. You're looking at Petrolisthes elongatus, the New Zealand Half Crab. This particular specimen was found on Jetty Beach, South Bruny Island, Tasmania. What's a New Zealand creature doing on Tasmania? Good question. It's an introduced, foreign (alien?) species.

These half crabs are a variety of porcelain crab. But their name begs a question, doesn't it. What's the other half? Well, I can't find that out. My best guess is that it the other half is evil. What makes this not a true crab? For one, it's got three pairs of walking legs as opposed to the traditional four (the fourth pair of legs are used for cleaning). Lastly, this crab's abdomen can be flapped and extended (much like my own), and true crabs have no such functionality.

But I doubt the average 'true' crab walks up to a half crab and mocks it for its halfness, not with that claw action. A gargantuan version of this might be able to take Tokyo and Mothra on at the same time.

Thanks for the link, Ida.

Photo source: Nuytsia@Tas